Projection display device and projection optical machine thereof

Abstract

The present invention discloses a projection optical engine for a projection display device, comprising a light source component, an optical waveguide, an image source chip, and a projection lens; the optical waveguide is a plate-like structure, the surface of the first end of the optical waveguide is provided with a coupling element, and the surface of the second end of the optical waveguide is provided with a coupling element; the optical waveguide is used to couple the light output by the light source component into the optical waveguide through the coupling element, and the light is transmitted to the second end of the optical waveguide and coupled out through the coupling element to be incident on the image source chip, so that the image source chip reflects the outgoing projection light toward the second end of the optical waveguide, and the projection light is transmitted through the second end of the optical waveguide to be incident on the projection lens and output. In the projection optical engine of the projection display device of the present application, a flat optical waveguide is used instead of a polarization beam splitter, so that the overall structure of the projection optical engine is flattened, which is conducive to installation and use in devices such as AR glasses. The present application also provides a projection display device having the above-mentioned beneficial effects.

Description

Technical Field

[0001] The present invention relates to the technical field of optical systems, and in particular to a projection optical engine of a projection display device and a projection display device. Background Art

[0002] The projection light engine is one of the important components of the projection display device. It mainly consists of an illumination light source, an image source and a projection lens. The light output by the illumination light source is projected onto the image source, and the projection light with the projected image is reflected from the image source and output through the projection lens.

[0003] With the development of projection display technology and the increasingly widespread application of projection display devices, people have higher and higher requirements for the convenience of carrying and using display devices. Therefore, how to reasonably set the shape structure of projection display devices in various application devices is one of the issues that the projection display technology industry needs to study. Summary of the Invention

[0004] An object of the present invention is to provide a projection optical engine for a projection display device and a projection display device, which are conducive to the application of the projection display device in various different environments.

[0005] To solve the above technical problems, the present invention provides a projection optical engine for a projection display device, comprising a light source component, an optical waveguide with a first end disposed on an output optical path of the light source component, an image source chip and a projection lens respectively disposed on opposite sides of a second end of the optical waveguide;

[0006] The optical waveguide is a plate-shaped structure, a coupling element is provided on the surface of the first end of the optical waveguide, and a coupling element is provided on the surface of the second end of the optical waveguide;

[0007] The optical waveguide is used to couple the light output by the light source component into the optical waveguide through the coupling element. The light is transmitted to the second end of the optical waveguide and coupled out through the coupling element to be incident on the image source chip, so that the image source chip reflects the output projection light toward the second end of the optical waveguide, and the projection light is transmitted through the second end of the optical waveguide and is incident on the projection lens and output.

[0008] Optionally, the light source component includes a light source and a light wave modulation device provided on an output light path of the light source; the light wave modulation device is used to modulate the light output by the light source into a first circularly polarized light;

[0009] A dimming device is provided between the image source chip and the outcoupling element; the dimming device is used to modulate the projection light emitted from the image source chip into a second circularly polarized light;

[0010] The first circularly polarized light and the second circularly polarized light have opposite rotation directions, and the outcoupling element is a polarization holographic grating that reflects and diffracts the first circularly polarized light and transmits the second circularly polarized light.

[0011] Optionally, the image source chip is an LCOS chip; and the dimming device is a first quarter wave plate.

[0012] Optionally, the light wave modulation device includes a polarizer and a second quarter wave plate, and the angle between the fast and slow axes of the second quarter wave plate and the polarization direction of the polarizer is 45 degrees.

[0013] Optionally, the light source is a laser light source, and a speckle removal device is further provided on the output light path of the laser light source;

[0014] The speckle removal device is an electrically controlled polarizer device, comprising a speckle removal polarizer and a TN liquid crystal cell, wherein the speckle removal polarizer is arranged on the surface of the TN liquid crystal cell;

[0015] Alternatively, the spot removal device is an electrically controlled PDLC panel.

[0016] Optionally, the PDLC panel is arranged in contact with the first end surface of the optical waveguide or embedded in the first end of the optical waveguide.

[0017] Optionally, a beam expansion and collimation device is further provided between the light source and the light wave modulation device.

[0018] Optionally, the coupling element is any one of a surface relief grating, a holographic grating, and a PVG grating.

[0019] A projection display device comprises the projection optical engine of the projection display device as described in any one of the above items.

[0020] Optionally, the projection display device is AR glasses.

[0021] The present invention provides a projection optical engine for a projection display device, comprising a light source component, an optical waveguide with a first end arranged on an output light path of the light source component, an image source chip and a projection lens respectively arranged on two opposite sides of a second end of the optical waveguide; wherein the optical waveguide is a plate-like structure, a coupling element is arranged on the surface of the first end of the optical waveguide, and a coupling element is arranged on the surface of the second end of the optical waveguide; the optical waveguide is used to couple light output by the light source component into the optical waveguide through the coupling element, and the light is transmitted to the second end of the optical waveguide and coupled out through the coupling element to be incident on the image source chip, so that the image source chip reflects and emits projection light toward the second end of the optical waveguide, and the projection light is transmitted through the second end of the optical waveguide, incident on the projection lens, and output.

[0022] In the projection optical machine of the projection display device of the present application, the light source component and the image source chip are respectively arranged at the first end and the second end of the optical waveguide, so that the illumination light output by the light source component is transmitted to the second end of the optical waveguide through total reflection in the optical waveguide and then coupled out and input into the image source chip. Compared with the structure in the prior art that usually uses square and large optical elements such as polarization beam splitters to transmit the light beam output by the light source component to the surface of the image source chip, the plate-shaped optical waveguide has a smaller thickness than the polarization beam splitter, which is beneficial to reducing the overall volume of the projection optical machine and making the overall structure of the projection optical machine flat, which is beneficial to installation and use in devices such as AR glasses.

[0023] The present application also provides a projection display device having the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A schematic diagram of the optical path structure of a conventional projection optical machine;

[0026] Figure 2 Schematic diagram of the optical path structure of the projection optical machine of the projection display device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The projection light machine of traditional projection display equipment is as follows Figure 1 As shown, a polarization beam splitter 02 is generally required to be set on the output light path of the lighting system 01. The illumination light is guided to the surface of the image source 03 through the polarization beam splitter 02 and then transmitted to the lens 04 through the polarization beam splitter 02 to be output to the display device.

[0028] The polarization beam splitter 02 is a cubic structure formed by splicing two prisms, which occupies a large space volume. As a result, the structure volume of the entire projection light machine is large, which also makes it difficult to adjust the shape of the projection light machine to adapt to the installation of various display devices.

[0029] For example, when the projection light engine is applied to AR glasses, the projection light engine is generally set in the temples of the glasses, and the polarization beam splitter 02 is a cubic structure, which will cause the thickness of the entire projection light engine to be larger, and then cause the thickness of the temples to be larger, making the temples of the projection light engine glasses too wide or too thick, giving users an uncomfortable usage experience.

[0030] Of course, there are also optical elements such as prisms and beam splitters in the existing technology to replace the polarization beam splitter, but the space volume occupied by these optical elements is similar to that of the polarization beam splitter and cannot have a substantial impact on the overall structure of the projection optical machine.

[0031] To this end, the projection light engine of the projection display device provided in this application can reduce the overall thickness of the projection light engine to a certain extent to achieve flattening of the projection light engine, which is conducive to adapting the projection light engine to the application of various different display devices.

[0032] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0033] like Figure 2 As shown, Figure 2 A schematic diagram of the projection optical engine structure of a projection display device provided in an embodiment of the present application, wherein the projection optical engine may include:

[0034] Light source component 1; based on the projection needs of the projection display device, the general light source component 1 adopts a component that can output white light. A red, green and blue light source can be configured in the light source component 1, and white light is obtained by uniformly mixing the three light sources.

[0035] An optical waveguide 2 having a first end provided on an output optical path of the light source component 1; an image source chip 3 and a projection lens 4 respectively provided on opposite sides of a second end of the optical waveguide 2;

[0036] The optical waveguide 2 is a plate-shaped structure, and a coupling element 21 is provided on the surface of the first end of the optical waveguide 2, and a coupling element 22 is provided on the surface of the second end of the optical waveguide 2;

[0037] The optical waveguide 2 can generally be a transparent plate with a plate-like structure or other shapes, and a refractive index greater than that of air. For example, it can be a transparent glass plate, and a transparent plastic plate is not excluded, as long as light can be transmitted by total internal reflection within the optical waveguide 2. The coupling element 21 can be any of a surface relief grating, a holographic grating, and a PVG grating. Similarly, the coupling element 22 can also be a grating structure. Of course, the coupling element 22 and the coupling element 21 can also be replaced by prisms or the like, and can be laminated at the ends of the optical waveguide 2.

[0038] The optical waveguide 2 is used to couple the light output by the light source component 1 into the optical waveguide 2 through the coupling element 21, conduct it to the second end of the optical waveguide 2 through total reflection, and couple it out from the optical waveguide 2 through the coupling element 22 to be incident on the surface of the image source chip 3, so that the light incident on the surface of the image source chip 3 forms a projection light, and is transmitted through the second end of the optical waveguide 2 to be incident on the projection lens 4 and output.

[0039] like Figure 2 As shown, the optical waveguide 2 is generally a plate-like structure, specifically a strip-like plate-like structure, with a thickness less than that of the polarization beam splitter. The light source component 1 is disposed at the first end of the optical waveguide 2. The light output by the light source component 1 is incident from the first end of the optical waveguide 2. The first end of the optical waveguide 2 is provided with a coupling element 21, so that the light output by the light source component 1 is coupled from the first end of the optical waveguide 2 into the optical waveguide 2, causing the light to be transmitted by total reflection within the optical waveguide 2. When the light is totally reflected in the optical waveguide 2 and transmitted to the second end of the optical waveguide 2, it is coupled out from the second end of the optical waveguide 2 through the coupling element 22 at the second end of the optical waveguide 2. An image source chip 3 is disposed on the coupling optical path, so that the coupled light is incident on the surface of the image source chip 3 to form a projection light reflected from the surface of the image source chip 3. The projection light is then transmitted through the second end of the optical waveguide 2 and incident on the projection lens 4 located on the other side of the second end of the optical waveguide 2 before being emitted.

[0040] based on Figure 1 It can be determined that the projection light machine provided in this application adopts a flat-structured optical waveguide 2 instead of a polarization beam splitter, compared with the conventional projection light machine that adopts a polarization beam splitter, which reduces the overall thickness of the projection light machine to a certain extent and realizes the flat structure of the projection light machine, so that the projection light machine can adapt well to narrow and long installation environments such as the temples of glasses, which is conducive to the widespread application of projection display equipment.

[0041] Furthermore, if Figure 1 As shown, the image source chip 3 and the projection lens 4 are respectively arranged on either side of the second end of the optical waveguide 2. The projection light emitted from the image source chip 3 needs to pass through the optical waveguide 2 before it can be incident on the projection light. However, the outcoupling element 22 at the second end of the optical waveguide 2 inevitably affects the transmittance of the projection light when the projection light passes through the second end of the optical waveguide 2. As a result, only a portion of the projection light can be incident on the projection lens 4, reducing the brightness of the projected image formed by the projection light output by the projection lens 4 and affecting the imaging effect of the projection display device.

[0042] To this end, in an optional embodiment of the present application, the light source component 1 includes a light source 10 and a light wave modulation device 12 provided on an output light path of the light source 10;

[0043] The light wave modulation device 12 is used to modulate the light output by the light source 10 into a first circularly polarized light;

[0044] A dimming device 5 is provided between the image source chip 3 and the outcoupling element 22; the dimming device 5 is used to modulate the projection light emitted from the image source chip 3 into a second circularly polarized light;

[0045] The first circularly polarized light and the second circularly polarized light have opposite rotation directions, and the outcoupling element is a polarization holographic grating that reflects and diffracts the first circularly polarized light and transmits the second circularly polarized light.

[0046] For example, the image source chip 3 may be an LCOS chip, and the dimming device 5 provided between the image source chip 3 and the outcoupling element 22 may be a first quarter-wave plate with an adjustable angle;

[0047] The first quarter wave plate is used to convert the first circularly polarized light coupled out from the optical waveguide 2 into linearly polarized light incident on the image source chip 3, and to convert the linearly polarized light reflected from the surface of the image source chip 3 into second circularly polarized light;

[0048] like Figure 2 As shown, the light wave modulation device 12 is used to modulate the light output by the light source 10 into a first circularly polarized light; the first circularly polarized light is coupled into the optical waveguide 2 through the coupling element 21 and transmitted to the second end of the optical waveguide 2. Because the coupling element 22 is a polarization holographic grating, it reflects and diffracts the first polarized light, so that the first circularly polarized light can be coupled out of the optical waveguide 2 and incident on the first 1 / 4 wave plate. After passing through the first 1 / 4 wave plate, the first circularly polarized light can form linearly polarized light and be incident on the surface of the image source chip 3. Because the image source chip 3 is an LCOS chip, its surface can reflect the outgoing projection light, and the projection light is also linearly polarized light. The projection light can form a second circularly polarized light after passing through the first 1 / 4 wave plate. In addition, by reasonably setting the first 1 / 4 wave plate and the light wave modulation device 12, the rotation direction of the second circularly polarized light can be opposite to that of the first circularly polarized light. The polarization holographic grating used in this embodiment is a grating that reflects and diffracts the first circularly polarized light and transmits the second circularly polarized light. Therefore, when the second circularly polarized light enters the optical waveguide 2 and then enters the polarization holographic grating, it can be efficiently transmitted from the polarization holographic grating and enter the projection lens.

[0049] It should be noted that in this embodiment, the rotation direction of the first circularly polarized light and the second circularly polarized light refers to whether the two circularly polarized lights are left-handed circularly polarized light or right-handed circularly polarized light, and whether the first circularly polarized light and the second circularly polarized light are left-handed circularly polarized light or right-handed circularly polarized light is determined by the light wave modulation device 12 and the first quarter-wave plate. The rotation direction of the second circularly polarized light is opposite to the rotation direction of the first circularly polarized light, which means that when the first circularly polarized light is left-handed circularly polarized light, the second circularly polarized light is right-handed circularly polarized light; conversely, when the first circularly polarized light is right-handed circularly polarized light, the second circularly polarized light is left-handed circularly polarized light. Regardless of which of the first circularly polarized light and the second circularly polarized light is left-handed circularly polarized light and which is right-handed circularly polarized light, it is sufficient to ensure that the outcoupling element 22, i.e., the polarization holographic grating, reflects and diffracts the first circularly polarized light and transmits the second circularly polarized light.

[0050] It should be noted that, in actual applications, converting the projection light output from the image source chip 3 into the second circularly polarized light is not limited to the use of the first 1 / 4 wave plate or other dimming device 5. For example, if the image source chip 3 uses an LCOS chip that has a 1 / 2 wave plate function, and the LCOS chip just satisfies the phase difference between the reflected image light and the incident light is π or an odd multiple thereof, then there is no need to use the dimming device 5, and the projection light output by the LCOS chip itself is the second circularly polarized light.

[0051] The light wave modulator 12 may include a polarizer 121 and a second quarter wave plate 122, wherein the angle between the fast and slow axes of the second quarter wave plate 122 and the polarization direction of the polarizer 121 is 45 degrees. Of course, the present application does not exclude the use of other light wave modulators.

[0052] Therefore, through the mutual cooperation between the light wave modulation device 12, the first 1 / 4 wave plate and the polarization holographic grating arranged at the second end of the optical waveguide 2, the separation of the effective projection light can be completed, and to a large extent, the absorption and reflection of the projection light by the coupling element 22 when the projection light is transmitted through the second end of the optical waveguide 2 to the projection lens 4 is avoided, thereby improving the transmittance of the coupling element 22 to the projection light, and then improving the brightness of the projection light output by the projection optical machine, thereby ensuring the display effect of the projection display device.

[0053] Furthermore, the light source 10 of the projector can generally be a laser light source or an LED light source. Both light-emitting diodes (LEDs) and laser light sources are primary color light sources. In addition to their color advantages, they also have the advantages of small optical etendue and good stability. This greatly reduces the complexity of the subsequent lighting system of the light source 20, thereby achieving a high degree of integration and reducing the system size, making them very suitable as light sources for micro-projection display systems.

[0054] However, when a laser light source is used, laser speckles exist in the light spots output by the light source 10, which may affect the imaging effect of the output projection light to a certain extent. Therefore, in an optional embodiment of the present application, a speckle removal device is further provided.

[0055] The speckle removal device can be provided in various configurations. For example, the speckle removal device can be an electrically controlled polarizer, which can include a TN liquid crystal cell and a speckle removal polarizer disposed on a surface of the TN liquid crystal cell, wherein the polarizer and the TN liquid crystal cell together form the electrically controlled polarizer.

[0056] When no external electric field is applied to the TN liquid crystal cell, the polarization direction of the incident light is deflected 90 degrees as it passes through the liquid crystal layer, following the twisting direction of the liquid crystal molecules. However, when a voltage is applied to the liquid crystal cell and reaches a certain value, the long axis of the liquid crystal molecules is deflected along the direction of the electric field, and the polarization direction of the outgoing light remains unchanged. The polarizer can be controlled by a circuit to make random and rapid changes according to the Hadamard matrix arrangement. As the voltage applied to the liquid crystal cell changes, the polarization direction of the transmitted light also changes. The pattern at each moment satisfies the Hadamard matrix distribution, and Hadamard matrices of the same size are orthogonal, making the coherence of the transmitted light approach zero at any moment. The frequency of the electric field must exceed the human eye's resolution limit of 60Hz, making it impossible for the eye to detect changes in the light field. This effectively suppresses or eliminates laser speckle.

[0057] In addition, the speckle-eliminating polarizer in the speckle-eliminating device and the polarizer in the light wave modulation device may be the same polarizer, or they may be two different polarizers.

[0058] Alternatively, the speckle removal device can utilize an electrically controlled PDLC panel. Circuitry controls the PDLC panel to undergo random, rapid changes according to the Hadamard matrix arrangement. As the voltage changes, the polarization direction of the transmitted light also changes. The pattern at each moment adheres to the Hadamard matrix distribution, and Hadamard matrices of the same size are orthogonal, ensuring that the coherence of the transmitted light at any moment approaches zero. The frequency of the electric field must exceed the human eye's resolution limit of 60 Hz, rendering the changes in the light field indistinguishable to the human eye. This effectively suppresses or eliminates laser speckle.

[0059] The electrically controlled PDLC panel can be embedded inside the first end of the optical waveguide 2, or can be set on the first end surface of the optical waveguide 2, so that the light beam output by the light source 10 is modulated into circularly polarized light by the light wave modulation device 12 and then coupled into the optical waveguide 2 through the electrically controlled PDLC panel.

[0060] To further enhance the imaging quality of the projection light emitted by the projection engine, a beam expander and collimator 11 can be further provided on the output optical path of the light source 10. This beam expander and collimator 11 is provided between the light source 10 and the light wave modulator 12 and can include a beam expander lens and a collimator lens. The light output by the light source 10 passes through the beam expander and collimator lenses, forming a parallel beam that is incident on the light wave modulator 12.

[0061] The present application also provides an embodiment of a projection display device, comprising a projection light engine as described in any of the above embodiments. A display device is provided on the output light path of the projection light engine, and a user can view a projected image displayed on the display device by inputting the projection light output by the projection light engine into the display device.

[0062] For example, the projection display device may be AR display glasses, and the projection light engine is disposed in the temples of the AR glasses. Because the projection light engine in this application tends to be flatter in appearance, it is convenient for installation in narrow temple structures, thus avoiding the problem of AR glasses having overly large temples that would result in a poor user experience.

[0063] Of course, the projection display device in this application does not exclude other types of projection display devices. Any projection display device that includes a projection optical machine as shown in any of the above items should fall within the scope of protection of this application.

[0064] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device comprising a series of elements are inherent to the elements. In the absence of further restrictions, the elements limited by the statement "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements. In addition, the above-mentioned technical solutions provided in the embodiments of the present application are not described in detail in accordance with the corresponding technical solutions in the prior art to achieve the same principle, so as to avoid excessive elaboration.

[0065] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A projection light engine for a projection display device, characterized in that: The optical waveguide comprises a light source component, a light guide having a first end arranged on an output light path of the light source component, and an image source chip and a projection lens respectively arranged on two opposite sides of a second end of the light guide; The optical waveguide is a plate-shaped structure, a coupling element is provided on the surface of the first end of the optical waveguide, and a coupling element is provided on the surface of the second end of the optical waveguide; The optical waveguide is used to couple the light output by the light source component into the optical waveguide through the coupling element, and the light is transmitted to the second end of the optical waveguide and coupled out through the coupling element to be incident on the image source chip, so that the image source chip reflects and emits projection light toward the second end of the optical waveguide, and the projection light is transmitted through the second end of the optical waveguide and is incident on the projection lens and output; The light source component includes a light source and a light wave modulation device arranged on the light output path of the light source; The light wave modulation device is used to modulate the light output by the light source into a first circularly polarized light; the light wave modulation device includes a polarizer and a second quarter wave plate, and the angle between the fast and slow axes of the second quarter wave plate and the polarization direction of the polarizer is 45 degrees; A dimming device is provided between the image source chip and the outcoupling element; the dimming device is used to modulate the projection light emitted from the image source chip into a second circularly polarized light; The first circularly polarized light and the second circularly polarized light have opposite rotation directions, and the outcoupling element is a polarization holographic grating that reflects and diffracts the first circularly polarized light and transmits the second circularly polarized light. The light source is a laser light source, and a speckle removal device is also provided on the output light path of the laser light source; The speckle removal device is an electrically controlled polarizer device, comprising a speckle removal polarizer and a TN liquid crystal cell, wherein the speckle removal polarizer is arranged on the surface of the TN liquid crystal cell; Alternatively, the spot removal device is an electrically controlled PDLC panel.

2. The projection light engine of the projection display device according to claim 1, wherein: The image source chip is an LCOS chip; the dimming device is a first quarter wave plate.

3. The projection light engine of the projection display device according to claim 1, wherein: The PDLC panel is arranged in contact with the first end surface of the optical waveguide or embedded in the first end of the optical waveguide.

4. The projection light engine of the projection display device according to claim 1, wherein: A beam expansion and collimation device is also provided between the light source and the light wave modulation device.

5. The projection light engine of the projection display device according to claim 1, wherein: The coupling element is any one of a surface relief grating, a holographic grating and a PVG grating.

6. A projection display device, characterized in that: A projection optical engine comprising the projection display device according to any one of claims 1 to 5.

7. The projection display device according to claim 6, wherein: The projection display device is AR glasses.

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